EP1416636A2 - Sensor element for a capacitive touch switch with an electrically conductive element and method of producing the same - Google Patents

Abstract

A capacitive contact sensor (11) has an elastic compressible body with alternate conducting and insulating zones between the circuit board (30) electrical contacts (32) and the upper surface (14) forming the shunt capacitances (Cp).

Description

The invention relates to a sensor element device according to the Preamble of claim 1 and a method for producing a Body as a sensor element for a capacitive sensor element device according to the preamble of claim 15.

Such sensor element devices are for example from the EP 859 467 B1 known. There is a sensor element with a body described, which is approximately elongated and cylindrical or barrel-shaped is. As can be seen from this prior art, for sensor elements arranged next to one another or by these formed touch switch needed several such bodies, which are arranged on a circuit board. As a manufacturing process describes how such bodies from an automatic assembly machine be cut to length from a long pole.

Task and solution

The invention has for its object a sensor element device mentioned above zu as well as a method mentioned at the beginning create, on the one hand, the body as a new sensor element is trained and has expanded functionality as well as the method for making this body is simplified.

This task is solved by a sensor element device the features of claim 1 and a method with the features of claim 15. Advantageous and preferred embodiments the invention are the subject of further claims and are in following explained in more detail. The wording of the claims is by express Reference made to the content of the description.

According to the invention, the sensor element device has a three-dimensional shape and elastically compressible body on which the sensor element forms. It is electrically conductive and extends at least in an area from an electrical contact to one Sensor element surface on the other hand. He points out according to the invention different areas. On the one hand, this is at least one conductive Area that is between an electrical contact and a sensor element surface extends and continuously electrical is conductive. There is also at least one isolating area provided that is not electrically conductive. Between several conductive Areas there is at least one isolating area. So can advantageously alternate conductive areas and insulating areas be arranged side by side. So it is possible according to the invention to create a single and unitary body that acts as one single and more manageable unit multiple sensor elements and thus forms several touch switches.

The sensor element surface is advantageous from the surface of a Formed part of a conductive region. The sensor element surface can of the contact surface between part of a conductive area and a cover on which the sensor element device is present, be formed. So it can be on a separate surface can be dispensed with in order to reduce the manufacturing expenditure. This The principle is known from EP 859 467 B1, in this regard is expressly referred to.

Another advantage is that not only a lot of smaller ones Body is replaced by a single and larger body. It can further simplify assembly processes, since no more many parts are handled and possibly used or put on must, but only a single part.

Furthermore, especially in comparison with the aforementioned EP 859 467 B1, recognizable that the individual sensor element body as they have been used so far, are cumbersome to use their sometimes small size. A larger body according to the invention on the other hand, it is easier to handle.

The plurality of conductive areas and the at least one insulating area The area can be mechanically and firmly connected to one another. Advantageous they are connected to each other in such a way that they are, so to speak, unsolvable are, so do not go apart on their own but only by applying force. They are particularly preferably formed in one piece.

The areas are advantageous between the electrical contact and the sensor element surface elongate and have an extension direction in that direction. In this direction all conductive areas advantageously run, that is to say particularly advantageously parallel to each other. It is also possible to use the isolating areas to run in this direction. It is special advantageous if the areas are cylindrical with a round or angular shape Cross-section.

The body is advantageously made of a rubber-like material to the to have elastic and compressible properties. This can for example, a foam, with soot or metal deposits electrical conductivity is achieved. For more precise designs this sensor element body, in particular with regard Manufacturing, material properties or composition, is express referred to EP 859 467 B1 and US Pat. No. 5,087,825, the wording of which is hereby expressly referred to is made to the content of the description.

The body can be part of a strand, i.e. a very long length exhibit. The aforementioned direction of extension of the areas can run perpendicular to the longitudinal direction of the strand. This means, that the strand is designed to have a large number has adjacent conductive and insulating areas.

The aforementioned strand can, for example, in a basic state be straight after manufacture. This is particularly advantageous on its longitudinal direction, so it's a straight strand. According to an advantageous training he can in a direction transverse to Direction of extent of the areas can be bendable, in particular elastic be bendable. This has the advantage that, for example, an arc arranged sensor elements can be formed with a single body. For this purpose, only the body in the desired manner and Bent way, which is easily possible due to the elasticity. With his Attachment to a circuit board or the like or behind a control panel or the like, the curved shape can be fixed. So are e.g. circular arrangements are also possible.

As an alternative to such a flexible strand, the body can already be designed in a form that can be predetermined as desired, that is also zigzag or in forms that can hardly be produced by bending. This shape can be particularly advantageous by manufacturing, in particular Joining the individual areas can be achieved.

The spacing of areas from one another, in particular their total Dimensions such as cross section and length are at least some conductive areas the same. All conductive are particularly advantageous Areas trained equally. This has mainly manufacturing technology Advantages such that, for example, from a long bar material the conductive areas can be separated and together with insulating areas, for example in the same way are produced, assembled into a strand-like sensor element can be.

The areas can be in addition to an elongated strand-like formation form a body that is field-like or flat. Different areas, in particular conductive and insulating, can thus be used Areas alternating in both planar extents of the Body and be connected. It is particularly advantageous provided that in turn the conductive areas in each direction are separated from each other by isolating areas. The resulting one Body can either form a closed surface or recesses or have breakthroughs. It is therefore possible that in the direct connection between two closest to each other conductive areas, which each form sensor elements, either an isolating area or an isolating air gap. The body can be designed such that it is cut to size can be, for example with blades or with a laser. alternative or in addition it can be provided that at a connection point two areas of the body can be separated. This can for example by pulling or tearing by hand and without Aids are made. Thereby the connection of the areas, which For example, an adhesive can be separated without the to damage individual areas yourself.

The electrical contacting for the conductive areas advantageously has Contacts, which are particularly advantageous as a surface and Contact fields can be formed. It is advantageously provided that the contacts are at least the distance between two conductive areas have each other or even an even larger one. Especially In a preferred embodiment it can be provided that between two contacts closest to each other several, for example three or four conductive areas are provided. So be direct contacted only those areas that are in contact with the contacts. The conductive areas in between are not direct Contact us.

It can be provided that an insulating area between conductive A dielectric forms in such a way that between the conductive areas cross capacitance and thus capacitive electrical Form connections. In this way, an electrical Connection also to conductive areas, which are not direct connected to a contact. This can make it possible less Requires contacts as conductive areas and thus sensor element surfaces available. About the aforementioned cross capacities can also evaluate these sensor element surfaces become. For this purpose, an evaluation circuit must be designed accordingly, which is connected to the sensor element device and the contacts having. This is possible due to the fact that the Cross capacities are known. Thus, from one touch originating signal at one of the conductive areas over the known Cross capacities are determined at which point the touch has occurred and thus which particular signal is triggered shall be.

A conductive area, especially the entire body, can be attached to the an insulating side facing the electrical contact Have layer or the like. This makes it possible for the electrical contacting has elongated and towering contact pins. These bump into the insulating body when the body is put on Layer into the conductive area and thus provide the electrical Contact her. This can allow whole strand-like or Place the plate-like body exactly positioned on a circuit board. The circuit board can carry contact pins, which at precisely predetermined Pierce through the insulating layer and a desired one Establish contact to individual conductive areas. Place other exposed contacts or solder joints on the circuit board no unwanted contact and prevent malfunction.

A conductive area is advantageously one or more insulating Jacketed areas adjacent. It is completely advantageous from isolating Surrounding areas.

In the aforementioned and inventive method of manufacture of a sensor element body, conductive areas are formed, for example according to the aforementioned type. They consist of electrical conductive, flexible and elastically compressible material. These conductive areas are connected by insulating areas, which, as has also been described above, consists of spatially changeable, consist of elastically compressible and insulating material. Such areas can, for example, be cylindrical Pins or the like are lined up side by side. A connection can be done by gluing, among which primarily a material connecting Connection is to be understood. For example, it can be thermal Hot melt or thermal welding.

There can be significantly more conductive and insulating areas side by side to be produced as a strand, as actually for a sensor element device is required. By separating individual The body is then made up as required becomes.

The above and further features go beyond the claims also from the description and the drawings, wherein the individual characteristics individually or in groups in form of sub-combinations in one embodiment of the invention and be realized in other areas and beneficial as well can represent protective designs for which protection is claimed here becomes. The division of the application into individual sections as well as sub-headings limit those made under these Statements not in their general validity.

Brief descriptions of the drawings

Figur 1.

Eine prinzipielle Darstellung der Anordnungsmöglichkeiten von leitfähigen und isolierenden Bereichen nebeneinander,

Figuren 2-4

Ausbildungen von strangartigen Sensorelement-Körpern in gerader oder gebogener Form, bei denen die elektrisch leitfähigen Bereiche von isolierenden Bereichen umgeben sind,

Figur 5

eine Ausgangsform zur Herstellung eines Sensorelements-Körpers in flächiger Form, aus dem einzelne Sensorelement-Körper durch Quer- und Längsschneiden hergestellt werden und

Figur 6

eine Darstellung eines Sensorelement-Körpers im Querschnitt , bei dem sich zwischen den elektrischen Kontaktierungen mehrere leitfähige Bereiche befinden.

Exemplary embodiments of the invention are shown schematically in the drawings and are explained in more detail below. The drawings show:

Figure 1.

A basic representation of the arrangement options of conductive and insulating areas next to each other,

Figures 2-4

Formations of strand-like sensor element bodies in straight or curved form, in which the electrically conductive areas are surrounded by insulating areas,

Figure 5

an initial form for producing a sensor element body in a flat form, from which individual sensor element bodies are produced by transverse and longitudinal cutting and

Figure 6

a representation of a sensor element body in cross section, in which there are several conductive areas between the electrical contacts.

Detailed description of the exemplary embodiments

FIG. 1 shows a strand-shaped sensor element device 11 or one Section of it. The sensor element device 11 consists of elongated, square cylindrical conductive areas 13. These have at one end on a sensor element surface 14, in Figure 1 up. On the downward-facing surface is an electrical one Contact area provided. This can be used for electrical contacting to a circuit or the like. Corresponds in this form the conductive area 13 is approximately an elastic sensor element, as it was called at the beginning. This is especially true for the function of the sensor element surface 14 and the electrical Contact area 15.

The sensor element device 11 has several of these conductive areas 13, which in the illustrated embodiment essentially are identical and run parallel to each other. you are through insulating areas 17 connected. It is between two conductive areas 13 an insulating area 17. So one Reaching the areas 13 and 17 achieved. Most of all will through the given mechanical connection which the sensor element device 11 manufactures as a single unit, achieved that it is easy to handle and install.

As previously stated, such a sensor element device can be used to form 11 areas 13 and 17 are manufactured separately and then connected to each other. Alternatively, one would be Kind of intermediate foaming possible. Either the conductive Areas 13 or the insulating areas 17 between the provided Areas of a different kind are injected accordingly a two-component syringe known in plastics processing.

Finally, there is the possibility of a single and in itself homogeneous Piece of raw material by processing individual areas these are either electrically conductive afterwards or electrically isolating. Possibilities for this would be, for example thermal or chemical processing or radiation.

As can be seen from FIG. 1 and should also be observed in general, is it is advantageous if the sensor element surface 14 and / or the electrical contact surfaces 15 are all in one plane. This simplifies it on the one hand, the production as a standardized strand material. On the other hand, use can be better planned. Under Alternatively, it may be advantageous to use different lengths of the To provide conductive areas 13 or the insulating areas 17.

FIG. 2 shows a variation of a sensor element device 111. This also has conductive, cylindrical elongated areas 113 on. They are upward in FIG. 2 with a sensor element surface 114 and down with an electrical contact surface 115 Mistake.

In deviation from the design from FIG. 1, the conductive ones are here Areas 113 except for the areas in which the sensor element surfaces 14 and the electrical contact surfaces 115 are made of material 117 surrounded. This material 117 forms the insulating areas 117. It is not only between two conductive areas 113, but also on their sides. For example, an unwanted lateral contacting of the conductive areas 113 can be avoided. Furthermore, the larger width of the strand-shaped sensor element device 111 achieved a simpler assembly under certain circumstances. Finally, shields or the like may be used be produced in this way, for example as an additional Layer on the very outside on the sides of the insulating material 117th

FIG. 3 in turn shows a strand-shaped sensor element device 211 shown, which corresponds approximately to that of Figure 2. Here are also conductive areas 213 laterally completely with insulating material surround. This forms the insulating areas 217, which are inter alia between two conductive areas 213.

The sensor element surfaces are in accordance with the design from FIG 214 and the electrical contact surfaces 215 free. Should this leaving surfaces 214 and 215 preferably in one plane each technically difficult and not exactly manageable simple remedy can be created. This exists advantageous in that a sensor element device is cut flat is used to create equal and flat surfaces 214 and 215 which at least does not survive the insulating material.

FIG. 4 in turn shows a further embodiment of a sensor element device 311 shown in strand form, which is roughly that of Figure 2 speaks. This is curved in a circle and almost with its ends formed abutting. Such a sensor element device 311 can either be formed by a straight line Strand material according to Figure 2 are produced. alternative the curved shape can be designed to be self-sustaining. this makes possible easier assembly.

The conductive areas 313 and thus also the sensor element surface 314 and the electrical contact surface 315 are longitudinally oval here educated. However, this does not matter and is essential also variable.

Furthermore, of the elongated shown in the figures and / or cylindrical shape of the conductive areas or the insulating Areas are deviated. For example, the surfaces 14 and 15 are made larger than the rest of the conductive areas as a cross section. Alternatively, the areas could be smaller be than the cross sections. This depends on what areas are related the sensor element sensitivity or triggering on the one hand and which cross sections with regard to electrical conductivity or other electrical properties are desired on the other hand.

It is easy to imagine that the sensor element device 311 is made of FIG. 4 could also be closed in the manner of a circular ring, so the front gap can be closed. This is in the area for the person skilled in the art from FIG. 4, which can be derived easily and without further ado technically feasible.

FIG. 5 shows a sensor element device 411, which is designed like a plate. Parallel to the expansion area of the Conductive areas 413 with sensor element surfaces run through the device 414 and electrical contact surfaces 415. Similar to in Figure 2 are also completely surrounding insulation in the form of insulating material 417 is provided.

The plate-shaped sensor element device 411 according to FIG. 5 can now by cutting into elongated and strand-shaped sensor element devices be divided according to Figure 2. This can be done accordingly the dash-dotted lines are cut or separated. These dash-dotted lines run perpendicular to the longitudinal extent of the conductive areas 413. The strand-like sensor element devices thus obtained can then again in accordance with the dashed Lines are cut to length. The embodiment shown in Figure 5 provides for a division into blocks of two and four; so with two or four conductive regions 413 each.

An embodiment of a sensor element device 411 according to FIG. 5 has the great advantage that it is essentially automatic or even can be produced fully automatically from plastic processing plants can. By cutting, separating or dimensioning accordingly can create the desired individual sensor element devices getting produced.

According to an exemplary embodiment, FIG. 6 shows how a Sensor element device 11 used corresponding to that of Figure 1 can be. A circuit board 30 carries, in addition to not shown Electronics and other components, contact fields 32. The contact fields 32 can be constructed from conductor tracks, for example.

The circuit board 30 runs parallel and at a certain distance to an underside of a glass ceramic plate 40. In between is the sensor element device 11 arranged so that it with the electrical Contact surfaces 15 to lie partly on contact fields 32 comes. The sensor element surfaces 14 in turn lie on the underside the glass ceramic plate 40. It should be noted that between individual contact fields 32 individual conductive areas 13 also with respect whose contact surfaces 15 can hang in the air, so to speak. There is therefore no electrical contact here.

As shown in FIG. 6, serial capacitances C _s are built up over the glass ceramic plate 40 as a dielectric. If a finger 41 touches the top of the glass ceramic plate 40 above a conductive area 13 or its sensor element surface 14, a capacitive coupling known per se is created. This can be evaluated as an actuation via a corresponding evaluation circuit, which is not described in more detail here.

In addition, however, in addition to the serial capacitances C _s , which are each formed above a conductive region 13, there are parallel capacitances Cp in FIG. These each exist between two adjacent conductive areas 13. They are formed by the electrical properties of the insulating areas 17, which are located between the electrically conductive areas 13. By means of these parallel capacitances Cp there is also an electrical connection of conductive areas 13 which are not contacted directly via their electrical contact surface 15. It is thus possible per se to reduce the number of contact fields 32 or, in any case, to set it lower than the number of conductive regions 13. Localization of the placement of a finger can be localized by evaluating the known corresponding transverse capacitances Cp. This is then only a question of the evaluation circuit.

With such a device, for example, it is acceptable Effort possible, several sensor element surfaces along a line or straight line 14 to provide, for example a scale or gradation. The contacting effort can be made accordingly be reduced.

Claims (17)

Sensor element device (11) for a capacitive touch switch, the sensor element device having an elastically compressible body (11, 111, 211, 311, 411) which is variable in terms of its shape and which is electrically conductive at least in some areas and differs from an electrical contact (15) extends to a sensor element surface (14), characterized in that the body has different regions, a conductive region (13) being continuously electrically conductive between the electrical contact (15) and the sensor element surface (14), an insulating one Area (17) is not electrically conductive and at least one insulating area (17) is located between several conductive areas (13). Sensor element device according to claim 1, characterized in that the sensor element surface (14) is formed by the surface of a part of a conductive region (13), wherein preferably the sensor element surface is formed by the contact surface between a part of a conductive region and a cover (40) on which the sensor element device (11) rests. Sensor element device according to claim 1 or 2, characterized in that the conductive regions (13) and the at least one insulating region (17) are mechanically connected to one another, in particular inseparably, wherein they are preferably in one piece. Sensor element device according to one of the preceding claims, characterized in that in the direction of extension from the electrical contact (15) to the sensor element surface (14) at least the conductive areas (13) run approximately in the same direction, preferably in parallel, in particular the insulating regions (17) also run in this direction and the regions are cylindrical. Sensor element device according to claim 4, characterized in that the regions (13, 17) are elongated when viewed in this direction of extension, wherein they preferably have a longer extension in the direction of extension than in another direction transverse to it. Sensor element device according to one of the preceding claims, characterized in that the body (11) consists of a rubber-like material which is made conductive, in particular with deposits. Sensor element device according to one of the preceding claims, characterized in that the body (11) is part of a strand, the direction of extension of the regions (13, 17) being perpendicular to the longitudinal direction of the strand, in particular the strand in the basic state, preferably in the longitudinal direction, is rectilinear, it being bendable in a direction transverse to the direction of extent of the regions. Sensor element device according to one of the preceding claims, characterized in that the regions form a field-like body which is expanded flatly perpendicular to the direction of extension, conductive (13) and insulating (17) regions being arranged alternately in both dimensions of the body and preferably the conductive ones Areas (13) are separated from each other in each direction. Sensor element device according to claim 8, characterized in that there is an insulating region (17) or an air gap in the direct connection between two closest conductive regions (13). Sensor element device according to one of the preceding claims, characterized by the fact that the body can be cut to size or separable at the junctures of two regions, preferably separable by means of manual removal or tearing off without aids. Sensor element device according to one of the preceding claims, characterized in that the electrical contact has contacts (32), in particular the contacts (32) being at least the distance between two conductive areas (13) from one another, and preferably a plurality of conductive areas (13) between them two closest contacts (32) are provided. Sensor element device according to one of the preceding claims, characterized in that a conductive region (13), in particular the body (11), is provided with an insulating layer on the side facing the electrical contact (32), the electrical contact being elongated and has towering contact pins that push through the insulating layer into the conductive area for producing the electrical contact. Sensor element device according to one of the preceding claims, characterized in that an insulating region (17) forms a dielectric between two conductive regions (13) such that transverse capacitances (Cp) or capacitive connections are formed between the conductive regions. Sensor element device according to one of the preceding claims, characterized in that a conductive region (13) is completely encased by one or more insulating regions (17) in the lateral direction transverse to its direction of extension. Method for producing a body (11) as a sensor element for a capacitive sensor element device, the body forming the sensor element, characterized in that conductive regions (13) are formed which consist of electrically conductive, shape-changing and elastically compressible material, and these conductive areas are connected by insulating areas (17), which consist of flexible, elastically compressible and insulating material. A method according to claim 15, characterized in that the connection is made by gluing, in particular by thermal hot melt gluing or welding. A method according to claim 15 or 16, characterized in that a strand (111, 211) in the direction of the expansion of conductive (13) and insulating (17) areas next to each other is manufactured considerably longer than a body (11), with individual bodies being separated getting produced.

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